• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.3
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• pp.395-402
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• 2015

In this paper, we propose an efficient gait trajectory generation method for the static stair climbing of a quadruped robot with mechanism of insectile legs, which has no collision with staris. First, we derive the kinematic and inverse models of a quadruped robot using the algebraic and geometrical methods, respectively. In the proposed method, we generate the stair locomotion trajectory of a sine wave after lifting a leg from the start position, and then determine the coefficient of the generated trajectory to avoid the collision with stairs. In addition, we make the gait sequence for the stable stair locomotion. Finally, we verify the effectiveness and applicability of the proposed stair locomotion method through computer simulations.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.10
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• pp.1269-1279
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• 1995

A mobile robot in a nuclear power plant is usually needed to equip the ability of going up and down stairs for a some kind of inspection. For this purpose, it is necessary for the mobile robot to figure out the size of stairs laid on a navigation path to gurantee robot's moving freely. In this paper, to measure the size of stairs existing in front of a mobile robot we designed the stair size recognition unit which can measure the stair's height and width using an ultrasonic sensor and/or a CCD camera. Also to obtain higher reliability of ultrasonic sensing data we proposed the horizontal sensing method. On the assupmtions that the mobile robot generates a trajectory while ascending stairs, we simulated it on a IBM compatible computer. The result showed that the suggested method satisfied our purpose. In a stair size estimation, the detected stair's height error was about .+-.3mm, and width was about .+-.5mm.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.181-187
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• 2017

Objective: The aim of the study was to compare & analyze on the variations of ground reaction force during ascending and descending of bus stair. Method: Simulated wooden stair of bus (raiser: 37.66 cm, width: 109 cm, tread: 29 cm) and GRF system (AMTI-OR-7/ AMTI., USA) was set up within experimental room. Adult female (n=8) performed ascending & descending of simulated bus stair, and variables analyzed consisted of TT (transfer-time), PVF (peak vertical force), LR (loading rate), DR (decay rate), CV (coefficient of variation) and AI (asymmetry index). Sample data from GRF cut off at 1,000 Hz. Results: TT showed shortest variation at phase 1 during descending, but longest variation at phase 1 during ascending of stair. PVF19 (Fz2, 100%) showed large pattern during descending than that of ascending, but rather showed small pattern during ascending of stair in case of PVF2 (Fz4). LR showed larger pattern during descending than that of ascending, but rather during ascending of stair in case of DR. Variation of CV (%) did not show difference between LR and DR, but showed higher possible occurrence of variation during descending of stair. Also AI (%) showed higher index during ascending than that of descending of stair. Conclusion: Because introduction of lowered bus stair has various realistic problems, if lined up at designated bus stopage exactly, rather can solve problems of inconvenience, reduce impulsive force and secure a stability of COG during ascending & descending of stair.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.1-8
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• 2017

PURPOSE: This study was to determine the changes of abdominal muscles activation according to the heel contact methods of stair ascent in healthy young adults. METHODS: 33 healthy young subjects (mean age: $26.37{\pm}9.72$ years, age range: 20-32 years) volunteered under two conditions. They were performed stair ascent with heel contact and without heel contact. The effects of heel contact methods were assessed using the surface electromyography (sEMG) analysis during stair ascent for activation of abdominal muscles (internal oblique; IO, transverse abdominis; TrA, external oblique; EO rectus abdominis; RA). The interventions were conducted over three trials in each method, and measurements were performed on each subject by one examiner in three trials. RESULTS: Our results revealed that there were significantly greater increase in the EMG activation of IO and TrA muscles in the performance of stair ascent with heel contact (p<.05) compared to those of stair ascent without heel contact. The results also showed that there were greater decrease in the ratio of abdominal muscle activation in those of stair ascent with heel contact compared with stair ascent without heel contact. CONCLUSION: These findings demonstrated that the method of stair ascent with heel contact would suggest positive evidence for improving activation of abdominal muscles.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.9
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• pp.1039-1048
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• 2015

In this paper, we propose an efficient stair locomotion method for a quadruped robot with mechanism of insectile legs using genetic algorithm(GA). In the proposed method, we first define the factors and the reachable region for the stair locomotion. In addition, we set the gene and the fitness function for GA and generate the gait trajectory by searching the landing position of a quadruped robot, which has the minimun distance of movement and the optimal energy stability margin(ESM). Finally, we verify the effectiveness and superiority of the proposed stair locomotion method through the computer simulations.

• Proceedings of the ESK Conference
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• 1995.10a
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• pp.87-90
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• 1995

Biomechanical can physchological approaches have provided the optimum stair dimensions but physiological approach has never been used in assessing the common method of assessing the optimum stair dimension. Therefore, this study was conducted to investigate the validity of the physiological measure of heart rate in assessing the optimum stair dimensions. Sixteen subjects were asked to walk up three different stairs with their normal walking speed. The results showed that the physiological approach with the heart rate difference was found to be valid in assessing the optimum stair dimension. The optimum stair dimension from this study (riser length for 185 mm and tread length for 310 mm) was chosen because it was similar to optimum dimension by the psychological approach (Irvine et al., 1990).

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.103-110
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• 2009

The purpose of this study is to suggest a proper tread of stairs using kinematic factors and moments of the lower-limb joints in the stair decent with the 3 different treads with boimechanical method in ergonomics. 9 subjects (body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26:{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms (the early (0-15 weeks), middle (16-27 weeks) and last (18-39 weeks). and they walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time were longer more and more. As extending treads of stair decent during pregnancy, speed, stride lengths and cycle time were increased. As extending the treads of stair decent, hip and ankle moments increased but knee moments decreased in sagittal plane. There were increasing or decreasing of moments by means of treads. These changes may account for relation between the treads of stair and moments in pregnant women. The main changes of pregnant women were joint moments and kinematic factors during pregnancy period because pregnancy makes them physical changes. It is possible that joints have connection with compensation each other to maximize stability and to control gait motion. In conclusion, we suggest that the tread of stair is longer than 26cm tread. and exercise programs to improve muscle activity were necessary where joint moments were small.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.1-10
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• 1996

In this paper, describe the automatic climbing wheelchair system use an articulated crawler mobile robot. This wheelchair system(call system) is composed of sensor detecting part and wireless communication part with PC. The sensor parts are consisted of sloping sensor and ultrasonic sensor part. The sloping sensor measures the sloping angle of system, and the ultrasonic sensor measures the distance of system's front wheel center from stair. PC will generate the operation data to climb up the stair using the measured data and make primitives for the system. At firsts This system transfer from sensor data to the PC. PC calculate the operation data to climb up the stair from the internal algorithm. We simulated the system in various stair angle slope($25^{\circ}$, $30^{\circ}$, $45^{\circ}$), and tested it on the real staircase with width 37cm, highlt 18cm, Angle $26^{\circ}$ . There were $0.350^{\circ}$ - $1.060^{\circ}$ Angle errors while climbing because adapted sensor has a precision $0.35^{\circ}$ in resolution. Finally, We implemented the sensor detecting part and the wireless communication park and practiced our system in 4cm/sec speed.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.4
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• pp.9-14
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• 2015

PURPOSE: Low-intensity exercise with restriction of blood flow has been proposed as an alternative exercise to secure the disadvantage of a high-intensity resistance exercise. However, studies of how affects the muscle using functional exercise are lacking. Thus, the purpose of this study was to investigate knee extensor muscle strength during stair exercise of functional exercise with leg blood flow restriction. METHODS: Twenty two healthy young adults with no history of musculoskeletal or neurogical disorder were participated in this study. participant were randomized into either non-restriction group(11 subject) or restriction group (11 subject). The restriction blood cuff attached to the proximal end of the leg. Measurement of knee extensor strength was used by cybex dynamometer. Data analyzed in independent t-test and paired t-test. RESULTS: Knee extensor muscle strength was significantly different between groups. Also, there were significant differences in the strength of knee extensor within the group. CONCLUSION: This study found that stair exercise with restriction of blood flow did influence to knee extensor muscle strength. These results will also be able to promote the effect of increasing the muscle power applied to functional exercise. Henceforth, studies will be made in the intervention method that can be applied to health vulnerable person.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.1 no.2
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• pp.70-73
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• 1987

This paper itltroduces a simple stair-case PWM using the pseudo-sinusoidal method. In a configuration of controller, the value of sine as a fundamental factor divided into stair-case level and the three-phase PWM inverter is composed by digital compound for each value of stair-case level. The three-phase output pulse at a fixed carrier frequency and a variable reference frequency is obtained under the effect of reduced harmonics. In this experiment, using the power FET as the switching device, 0.5 H.P. induction motor operation is performed when the switching frequency is 20KHz.